Might wearing an Apple Watch save you from a stroke or cardio problem?

Apple is careful not to make that direct claim. But the company, in collaboration with Stanford University School of Medicine, launched the Apple Heart Study app on Thursday that uses the heart rate sensor inside the Apple Watch to collect data on irregular heart rhythms. The study had been previously announced in September.

If an irregular heart rhythm is detected, participants in the study will be notified through the Apple Watch and on their iPhones. Should that occur, you’ll be offered a free consultation with a study doctor, and possibly an electrocardiogram (ECG) patch for additional monitoring.

Of course, at that point you'll likely also wish to consult your own physician.

Atrial fibrillation or AFib, is the leading cause of stroke, and responsible for some 130,000 U.S. deaths every year, Apple says. And since many people don’t experience symptoms, AFib often goes undetected.

A participant in the study merely has to download the app and wear the watch.

The way Apple explains it, a sensor inside the watch uses green LED lights flashing hundreds of times per second and light-sensitive photodiodes to detect the amount of blood flowing through the wrist. The sensor has an optical design that gathers signals from four distinct points on the wrist. Using software algorithms, the Apple Watch can isolate heart rhythms from other noise, and identify an irregular heart rhythm.

The Apple Heart Study collects stats from volunteer participants when you are wearing the Apple Watch.(Photo: Apple)

The study is open to U.S. participants 22 years of age or older. You must have an Apple Watch (Series 1 model or later) and an iPhone (model 5s or later). You must also confirm that you do not have AFib, or an atrial flutter. Taking anticoagulant medications is also a disqualifier.

Participants can leave the study at any time. Apple says it doesn’t have any identifying information on study participants.

According to Apple, more than 500 researchers and more than three million people have been using iPhones, the Apple Watch, and Apple's ResearchKit platform and software tools to participate in medical studies that range from autism to Parkinson’s disease.